Distribution patterns of soil microbial eukaryotes suggests widespread algivory by phagotrophic protists as an alternative pathway for nutrient cycling

Seppey, Christophe V. W.; Singer, David; Dumack, Kenneth; Fournier, Bertrand; Belbahri, Lassaâd; Mitchell, Edward A. D.; Lara, Enrique

doi:10.1016/j.soilbio.2017.05.002

Cited by 95 publications

(85 citation statements)

References 53 publications

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“…algae and lichens, suggesting that the importance of non‐vascular plants as a basal resource of soil food webs has been underestimated (Schmidt et al ., ; Potapov et al ., ; Potapov et al ., ). Supporting the importance of non‐vascular plants in soil food webs, a recent DNA‐based study showed that algivory is widespread among soil protists (Seppey et al ., ).…”

Section: Reconstructing Trophic Linksmentioning

confidence: 99%

Uncovering trophic positions and food resources of soil animals using bulk natural stable isotope composition

2018

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Despite the major importance of soil biota in nutrient and energy fluxes, interactions in soil food webs are poorly understood. Here we provide an overview of recent advances in uncovering the trophic structure of soil food webs using natural variations in stable isotope ratios. We discuss approaches of application, normalization and interpretation of stable isotope ratios along with methodological pitfalls. Analysis of published data from temperate forest ecosystems is used to outline emerging concepts and perspectives in soil food web research. In contrast to aboveground and aquatic food webs, trophic fractionation at the basal level of detrital food webs is large for carbon and small for nitrogen stable isotopes. Virtually all soil animals are enriched in C as compared to plant litter. This 'detrital shift' likely reflects preferential uptake of C-enriched microbial biomass and underlines the importance of microorganisms, in contrast to dead plant material, as a major food resource for the soil animal community. Soil organic matter is enriched in N and C relative to leaf litter. Decomposers inhabiting mineral soil layers therefore might be enriched in N resulting in overlap in isotope ratios between soil-dwelling detritivores and litter-dwelling predators. By contrast, C content varies little between detritivores in upper litter and in mineral soil, suggesting that they rely on similar basal resources, i.e. little decomposed organic matter. Comparing vertical isotope gradients in animals and in basal resources can be a valuable tool to assess trophic interactions and dynamics of organic matter in soil. As indicated by stable isotope composition, direct feeding on living plant material as well as on mycorrhizal fungi is likely rare among soil invertebrates. Plant carbon is taken up predominantly by saprotrophic microorganisms and channelled to higher trophic levels of the soil food web. However, feeding on photoautotrophic microorganisms and non-vascular plants may play an important role in fuelling soil food webs. The trophic niche of most high-rank animal taxa spans at least two trophic levels, implying the use of a wide range of resources. Therefore, to identify trophic species and links in food webs, low-rank taxonomic identification is required. Despite overlap in feeding strategies, stable isotope composition of the high-rank taxonomic groups reflects differences in trophic level and in the use of basal resources. Different taxonomic groups of predators and decomposers are likely linked to different pools of organic matter in soil, suggesting different functional roles and indicating that trophic niches in soil animal communities are phylogenetically structured. During last two decades studies using stable isotope analysis have elucidated the trophic structure of soil communities, clarified basal food resources of the soil food web and revealed links between above- and belowground ecosystem compartments. Extending the use of stable isotope analysis to a wider range of soil-dwelling organisms, including mi...

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Section: Reconstructing Trophic Linksmentioning

confidence: 99%

Uncovering trophic positions and food resources of soil animals using bulk natural stable isotope composition

2018

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“…Thecofiloseans have recently been clarified to be major algae grazers showing their significance in soil systems (Seppey et al. ), so that phaeodarians may play a similar role in marine ecosystems by grazing algae.…”

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Gazelletta kashiwaensis sp. nov. (Medusettidae, Phaeodaria, Cercozoa), Its Morphology, Phylogeny, Distribution, and Feeding Behavior

Nakamura

Somiya

Kanda³

et al. 2018

J Eukaryotic Microbiology

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A phaeodarian morphotype, characterized by the feet surrounded with forked pedal spines with anchor-like structures, was collected in the subtropical North Pacific. Considering the morphological and phylogenetic uniqueness, this morphotype is described as Gazelletta kashiwaensis sp. nov. The distribution of this new species is possibly affected by the Kuroshio Current. The feeding behavior of living phaeodarians was first filmed: the present new species floated in the water column stretching "protoplasmic webs" and collected diatoms by repeating the expansion and retraction of "pseudopodium-like tentacles".

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“…Still other protists in both aquatic and terrestrial habitats rely on algal prey (Busch and Hess ; Seppey et al. ), other protists and even small animals (Geisen et al. ).…”

Section: Discussionmentioning

confidence: 99%

The Response of Litter‐Associated Myxomycetes to Long‐Term Nutrient Addition in a Lowland Tropical Forest

Walker

Cedeño-Sanchez

Carbonero

et al. 2019

J Eukaryotic Microbiology

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Myxomycetes (plasmodial slime molds) are abundant protist predators that feed on bacteria and other microorganisms, thereby playing important roles in terrestrial nutrient cycling. Despite their significance, little is known about myxomycete communities and the extent to which they are affected by nutrient availability. We studied the influence of long‐term addition of N, P, and K on the myxomycete community in a lowland forest in the Republic of Panama. In a previous study, microbial biomass increased with P but not N or K addition at this site. We hypothesized that myxomycetes would increase in abundance in response to P but that they would not respond to the sole addition of N or K. Moist chamber cultures of leaf litter and small woody debris were used to quantify myxomycete abundance. We generated the largest myxomycete dataset (3,381 records) for any single locality in the tropics comprised by 91 morphospecies. In line with our hypothesis, myxomycete abundance increased in response to P addition but did not respond to N or K. Community composition was unaffected by nutrient treatments. This work represents one of very few large‐scale and long‐term field studies to include a heterotrophic protist highlighting the feasibility and value in doing so.

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Distribution patterns of soil microbial eukaryotes suggests widespread algivory by phagotrophic protists as an alternative pathway for nutrient cycling

Cited by 95 publications

References 53 publications

Uncovering trophic positions and food resources of soil animals using bulk natural stable isotope composition

Uncovering trophic positions and food resources of soil animals using bulk natural stable isotope composition

Gazelletta kashiwaensis sp. nov. (Medusettidae, Phaeodaria, Cercozoa), Its Morphology, Phylogeny, Distribution, and Feeding Behavior

The Response of Litter‐Associated Myxomycetes to Long‐Term Nutrient Addition in a Lowland Tropical Forest

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